1. Field of the Invention
The present invention relates to a structure for mounting pressure sensors which measure the pressure of a heat exchanging medium at high pressure and a heat exchanging medium at low pressure flowing in the cooling cycle in an air conditioning system for vehicles and the like, at an expansion valve or a piping joint connector of the air conditioning system.
2. Description of the Related Art
In recent years, the heightened global awareness of environmental issues and the need to conserve energy resources have prompted the automotive industry to strive for reductions in fuel consumption in automobiles. As one of the methods for responding to the demand for reduced fuel consumption in automobiles, the engine load resulting from driving the air conditioning system in the automobile may be reduced by lowering the idling rotation rate of the engine.
However, in order to lower the idling rotation rate, the rotation rate of the engine must be controlled finely in correspondence to changes in the pressure of the heat exchanging medium by measuring the pressure of the heat exchanging medium flowing in the low pressure passage as well as the pressure of the heat exchanging medium flowing in the high pressure passage in the cooling cycle of the air conditioning system.
For this purpose, a method whereby a high pressure side sensor and a low pressure side sensor are separately installed at a connecting passage at the high pressure side and a connecting passage at the low pressure side respectively to measure the pressures of the fluid body (heat exchanging medium) flowing inside the connecting passages and at the high pressure side and at the low pressure side, is disclosed in, for instance, Japanese Unexamined Patent Publication No. S63-101712, is adopted.
However, if pressure sensors are separately installed in the individual connecting passages as disclosed in Japanese Unexamined Patent Publication No. S63-101712 mentioned above, problems arise in that the number of parts must be increased, since mounting portions for installing the individual pressure sensors are required and in that the number of manufacturing steps must increase as well, since the individual pressure sensors must be mounted separately.